CN116092984B - Method for determining the positioning accuracy of a wafer transport device - Google Patents
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- H01L21/677—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for conveying, e.g. between different workstations
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Abstract
Embodiments of the present disclosure provide a method for determining positioning accuracy of a wafer transfer apparatus, the method comprising: a) Receiving a single target wafer from an equipment front end module EFEM using a wafer carrier and motion platform; b) Acquiring a first image of the single target wafer at a first predetermined position by using an imaging device; c) Moving the single target wafer from the first predetermined position to a second predetermined position using a wafer carrying and moving stage; d) Returning the single target wafer from the second predetermined position to the first predetermined position using the wafer carrying and moving stage; e) Repeating steps b), c) and d) n times, thereby obtaining n corresponding first images, wherein n is an integer much greater than 1; and f) based on n+1 of said first images, and obtaining the platform errors of the wafer bearing and moving platform in the X and Y directions.
Description
Technical Field
The present disclosure relates to the field of semiconductor wafer transport, and more particularly to a method of determining the positioning accuracy of a wafer transport apparatus.
Background
With the development of the heat in the semiconductor field, many semiconductor equipment manufacturers appear like blowout, and how to measure the precision of various wafer transmission equipment with higher efficiency, simpler and lower cost is important on the way of localization substitution.
The current precision measurement method mainly adopts the following steps: one is a method of measuring by a laser interferometer, which has the problems that: 1. the equipment has high specificity and high technical requirements for operators; 2. high cost and complex operation; 3. is easily interfered by external environment and has strict environmental requirements. Secondly, a method for photographing and measuring by a plurality of groups of cameras, which has the following problems: 1. redundancy of the camera system can lead to increased errors and is subject to assembly skill limitations by the assembler; 2. the levelness and the angle difference of the installation among the multiple groups of cameras can cause great interference on the test precision, such as whether the horizontal planes of the cameras are consistent when the cameras are installed, whether the shooting angles of the cameras are deviated, whether the fields of view of the cameras are identical, and the like, and the error which is difficult to avoid is caused to final data.
Disclosure of Invention
It is an object of the present disclosure to provide an improved method for determining the positioning accuracy of a wafer transfer device.
According to a first aspect of the present disclosure, there is provided a method of determining positioning accuracy of a wafer transfer apparatus, the method comprising: a) Receiving a single target wafer from an equipment front end module EFEM using a wafer carrier and motion platform; b) Acquiring a first image of the single target wafer at a first predetermined position by using an imaging device; c) Moving the single target wafer from the first predetermined position to a second predetermined position using the wafer carrying and moving stage; d) Returning the single target wafer from the second predetermined position to the first predetermined position using the wafer carrying and moving stage; e) Repeating steps b), c) and d) n times, thereby obtaining n corresponding first images, wherein n is an integer much greater than 1; and f) obtaining a platform error of the wafer bearing and moving platform in X and Y directions based on the n+1 first images.
It will be appreciated that by the above method, the stage errors of the wafer carrier and motion stage in the X and Y directions can be obtained simply.
Further, in some embodiments, the method further includes g) receiving m target wafers from the EFEM one by one using the wafer carrier and motion stage and moving each of the m target wafers one by one to the third predetermined location, where m is an integer substantially greater than 1; h) Acquiring second images of predetermined centrifugal points and third images of center points on each target wafer at the third predetermined positions one by using the imaging device, so as to obtain m corresponding second images and m third images, wherein the predetermined centrifugal points are predetermined points deviating from the center points of the corresponding target wafers; and i) obtaining a linear error of the EFEM in the X and Y directions and a rotational error in an R direction based on the m second images and the m third images, wherein R represents a rotational direction.
It will be appreciated that in this manner, the linearity errors of the EFEM in the X and Y directions and the rotational errors in the R direction may be further simply obtained.
In some embodiments, the step i) includes i 1) analyzing coordinates of center points in the m third images to obtain total center linear errors in both the X and Y directions of the EFEM and the wafer carrier and motion stage; i2 Based on both the total center point linear error and the stage error, linear errors of the EFEM in the X and Y directions are obtained.
In some embodiments, the step i 2) above comprises: subtracting the corresponding stage errors in the X and Y directions from the total center linear error in the X and Y directions to obtain linear errors in the X and Y directions, respectively, of the EFEM.
In some embodiments, step i) above further comprises: i3 Analyzing coordinates of the predetermined spin points of the m second images to obtain a total spin point error in both the X and Y directions for the EFEM and the wafer carrier and motion stage; i4 Subtracting the total center-point linear error from the total spin point error to obtain a rotational error of the EFEM in the R direction.
In some embodiments, step i) above further comprises: selecting one image of the m second images as a reference image; obtaining an offset distance of a predetermined centrifugation point (a') of each other image in the second image relative to a predetermined centrifugation point (B) of the reference image after subtracting the linear error of the EFEM; and calculating a central angle corresponding to the offset distance based on the offset distance, wherein a rotation error of the EFEM in the R direction is represented by a section between a minimum value and a maximum value of the central angle corresponding to the other image.
In some embodiments, step i) above comprises: identifying a predetermined straight line present on each second image; a rotational error of the EFEM in the R direction is obtained based on a slope analysis of the predetermined straight line on each second image.
In some embodiments, step i) above comprises: identifying two corner points of a predetermined polygon present on each second image; determining the slope of a connecting line of the two corner points; a rotational error of the EFEM in the R direction is obtained based on a slope analysis of the link on each second image.
In some embodiments of the present invention, in some embodiments, the first predetermined location is a location where the wafer carrier and motion stage initially receives the single target wafer from the EFEM.
In some embodiments, in step e) above, the second predetermined position is variable.
In some embodiments, the third predetermined position and the second predetermined position are different from or the same as each other.
In some embodiments, the value of n is greater than 30 and the value of m is greater than 30.
In some embodiments, the imaging device is a single camera.
According to a second aspect of the present disclosure, a wafer processing apparatus is provided. The wafer processing apparatus determines the positioning accuracy of a wafer transfer apparatus in the wafer processing apparatus by the method according to the first aspect.
According to a second aspect of the present disclosure, there is provided a computer readable medium storing computer readable instructions that, when executed by a processor, cause an apparatus to perform the method according to the first aspect.
It should also be appreciated that the descriptions in this summary are not intended to limit key or critical features of embodiments of the disclosure, nor are they intended to limit the scope of the disclosure. Other features of embodiments of the present disclosure will become apparent from the following description.
Drawings
The above and other features, advantages and aspects of embodiments of the present disclosure will become more apparent by reference to the following detailed description when taken in conjunction with the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements.
Fig. 1 illustrates an exemplary application scenario of a method for determining positioning accuracy of a wafer transfer apparatus according to an exemplary embodiment of the present disclosure.
Fig. 2 illustrates a flowchart of a method for determining positioning accuracy of a wafer transfer apparatus according to an example embodiment of the present disclosure.
Fig. 3 shows a schematic diagram of the rotational error in the rotational direction R caused by the equipment front end module EFEM.
Detailed Description
Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While certain embodiments of the present disclosure have been shown in the accompanying drawings, it is to be understood that the present disclosure may be embodied in various forms and should not be construed as limited to the embodiments set forth herein, but are provided to provide a more thorough and complete understanding of the present disclosure. It should be understood that the drawings and embodiments of the present disclosure are for illustration purposes only and are not intended to limit the scope of the present disclosure.
As described above, with the development of the semiconductor field, it is important to determine the positioning accuracy of each wafer transfer apparatus more efficiently, more simply and at lower cost. The present disclosure contemplates determining the accuracy of positioning of an associated wafer transport device, such as a wafer carrier and motion stage, or an equipment front end module (Equipment Front End Module or EFEM), during wafer transfer based on the wafer carrier and motion stage and an imaging device, such as an industrial camera, particularly a single camera.
To more clearly understand the concept of the present disclosure, fig. 1 illustrates a typical application scenario of a method for determining positioning accuracy of a wafer transfer apparatus according to an example embodiment of the present disclosure.
As shown in fig. 1, the method for determining the positioning accuracy of a wafer transport apparatus of an example embodiment of the present disclosure may be used in a wafer processing apparatus 1, which may include at least an Equipment Front End Module (EFEM) 2 and a wafer load and motion stage 3.
The EFEM 2 functions as a secure, clean mechanical transfer interface between a production line and an equipment process module (not shown). Generally, the front end of the EFEM is connected to the production line by means of a wafer cassette unloading system (Load Port), the rear end is connected to the functional module of the main body of the device, and the manipulator installed inside the EFEM is used for transferring wafers between the wafer cassette on the EFEM interface and the functional module of the rear end of the device, so as to ensure that the transferring process is always in a clean environment.
The wafer carrier and motion stage 3 may receive wafers transferred from the robots of the EFEM 2 and transport them to the associated equipment process modules (not shown) for corresponding wafer processing including, but not limited to, exposure, etching, cleaning, position sensing, cleaning, etc.
It will thus be appreciated that the accuracy of positioning of both the equipment front end module 2 and the wafer carrier and motion stage 3 described above is critical to accurate exposure, etching, etc.
According to the design of the present disclosure, the wafer processing apparatus 1 may further comprise an imaging apparatus 4, which may be, for example, an industrial camera, and may be an integrated part of the optical bench 5. The optics machine 5 may for example be arranged above the wafer carrier and motion stage 2 in order to enable imaging of a wafer carried on the wafer carrier and motion stage 2. In particular, in various embodiments of the present disclosure, the imaging device 4 preferably comprises only a single camera. That is, various embodiments of the present disclosure may facilitate the measurement of the positioning accuracy of the present disclosure for determining the wafer transfer device through a single camera. It will be appreciated that the use of a single camera may advantageously avoid problems that may occur with conventional multiple sets of cameras, such as: the levelness and angle difference of the installation among the multiple groups of cameras influence the test precision.
A flowchart of a method 200 for determining the positioning accuracy of a wafer transfer apparatus according to an example embodiment of the present disclosure will be described below in conjunction with fig. 2.
As shown in fig. 2, at block 210, a single target wafer is received from an equipment front end module EFEM using a wafer carrier and motion stage. The wafer carrier and motion stage and EFEM may be, for example, the wafer carrier and motion stage 3 and EFEM 2, respectively, previously shown in fig. 1, wherein the EFEM may use, for example, a robot to place a single target wafer on the wafer carrier and motion stage 3.
At block 220, a first image of the single target wafer at a first predetermined location is acquired using an imaging device. Preferably, the first predetermined location may be, for example, a location where the wafer carrier and motion stage 3 initially receives the single target wafer from the EFEM. It will be appreciated that in such a position, the positional error of the individual wafers will be entirely determined by the positional accuracy of the EFEM, which is advantageous for later more accurate determination of the errors of the EFEM and/or wafer carrier and motion stage. However, this is not limiting, and in other embodiments it is possible that the first predetermined position is a different position.
At block 230, moving a single target wafer from the first predetermined position to a second predetermined position using a wafer carrying and moving stage; returning the single target wafer from the second predetermined position to the first predetermined position using the wafer carrying and moving stage at block 240; and at block 250, repeating steps n times in blocks 220, 230 and 240 to obtain corresponding n first images, where n is an integer substantially greater than 1.
It will be appreciated that in the operations of blocks 230-250 described above, a single target wafer will be moved back and forth between a first predetermined position and a second predetermined position and imaged each time the first predetermined position is returned. It will also be appreciated that the accuracy of the positioning of the first predetermined position per return will depend entirely on the stage error of the wafer load and motion stage, and that the stage error of the wafer load and motion stage can be determined by analyzing the change in position of the first predetermined position per return.
In some embodiments, to more accurately reflect the platen error of the wafer carrying and moving platen, the second predetermined position may be selected to be a position relatively far from the first predetermined position. In still other embodiments, the first predetermined position may be constant and the second predetermined position may be variable, i.e., the second predetermined positions repeatedly performed in block 230 may be different from each other. It should be appreciated that this is not limiting and that in still other embodiments, both the first predetermined position and the second predetermined position may be variable or constant.
In some embodiments, the value of n may be greater than 30, 40, 50, 60, 70, 80, or 100. It will be appreciated that the larger the value of n, the more accurate will be the determination or calculation of the latter error.
At block 260, a stage error in the X and Y directions of the wafer carrier and motion stage is obtained based on the n+1 first images.
To more conveniently calculate the above-described platform error, in some embodiments, the first image based on n+1 may, for example, include: features in the n+1 first images are identified and the positional changes of the features are analyzed, and then the above-described platform error is obtained based on the positional changes. By way of example only, the feature may be, for example, a mark on a single target wafer as described above. These marks may be, for example, various shapes or patterns preformed on the wafer.
It will be readily appreciated that it is easy to identify the marks on the wafer, for example, for the grey scale image of the first image described above, the RGB values vary between 0 and 255, the color will change from black to white, the larger the number the brighter the pixel, the more energy. The Mark (Mark) on the wafer (e.g., r=g=b > 150) is more conspicuous with respect to its edge background color (e.g., r=g=b < 90), and in global, there is typically and only the edge of the Mark that has the greatest absolute value of the background color difference. Thus, the position coordinates of the mark (e.g., edge points or corner points on the mark) can be found by the color gamut gradient change. Further, the platform error fatx 0, faty 0 of the wafer carrying and moving platform in the X and Y directions can be obtained by analyzing the position changes of the position coordinates of the marks (e.g., edge points or corner points on the marks) in different first images. Further, in some embodiments, multiple feature points on the mark may be taken to reduce occasional errors, taking into account errors caused by a single point taking.
In still other embodiments, the first image based on n+1 first images may further preferably include: selecting one of the n+1 first images as a reference image, and analyzing the position deviation of the features of each other of the n+1 first images relative to the corresponding features in the reference image; and obtaining a deviation interval in which the position deviation exists based on the position deviation, wherein the deviation interval can be used for representing a platform error of the wafer bearing and moving platform in X and Y directions, namely, faty 0.
It should be noted that, the wafer carrying and moving platform generally performs translational motion only in the X and Y directions, so there is generally no positioning error in the Z direction and the rotation direction R. Therefore, it is sufficient to calculate only the stage errors of the wafer carrier and motion stage in the X and Y directions.
Having described how the stage errors in the X and Y directions of the wafer carrying and moving stage are obtained, the focus of the description is to be given on how the linear errors in the X and Y directions of the EFEM itself are obtained, as well as the rotational errors in the rotational direction R. Accordingly, the method 200 of determining the positioning accuracy of the wafer transfer apparatus of the present disclosure may further include:
at block 270, m target wafers are received from the EFEM one by one using the wafer carrier and motion stage and each of the m target wafers is moved one by one to the third predetermined position, where m is an integer much greater than 1.
In some embodiments, the third predetermined position may be a fixed position and may be different from or the same as the first predetermined position or the second predetermined position. Similarly, the third predetermined location may be selected at another location relatively far from the first predetermined location where the wafer carrying and moving stage initially receives the target wafer from the EFEM.
It will be readily appreciated that in the case of each wafer being moved to a fixed third predetermined position by the wafer carrier and motion stage, the positioning error of the wafer at that third predetermined position will depend on the total error of both the EFEM and the wafer carrier and motion stage, which may include both linear errors in the X and Y directions and rotational errors in the rotational direction R due to the EFEM, as well as errors due to the wafer carrier and motion stage (i.e., the previously determined stage errors X0, Y0).
In some embodiments, the value of m may be greater than 30, 40, 50, 60, 70, 80, or 100. It will be appreciated that the larger the value of m, the more accurate it will be in determining the correlation error.
At block 280, second images and third images of the center point of each target wafer at the third predetermined location are acquired one by one (i.e., wafer by wafer) using the imaging device to obtain corresponding m second images and m third images, wherein the predetermined center point is a predetermined point offset from the center point of the corresponding target wafer.
It should be appreciated that the predetermined spin points described above may be selected marks or other feature points on the wafer, and are optimally selected to be better the farther from the center point. In particular, the predetermined off-center point may be selected as a mark located on or near the edge of the wafer.
What needs to be explained here is: in some embodiments, the field of view of the imaging device may be rectangular with a length of less than 1mm, whereas for wafers typically over 200mm in size, it is difficult for the imaging device to capture the aforementioned center point and the predetermined off-center point in the same photograph. Therefore, in these embodiments, the second image of the predetermined centrifugal point and the third image of the center point may be obtained by different shots of the imaging device. However, this is not restrictive, and in an embodiment in which the field of view of the imaging apparatus is sufficient to cover the entire wafer, it is also possible to obtain the second image of the above-described predetermined centrifugal point and the third image of the above-described center point by one shot, in which case the second image and the third image may be regarded as different portions of the same image.
At block 290, a linear error of the EFEM in the X and Y directions and a rotational error in the R direction are obtained based on the m second images and the m third images, where R represents the rotational direction.
In some embodiments, the linear error of the EFEM in the X and Y directions and the rotational error in the R direction, respectively, may be calculated or determined.
For example, to obtain the linearity errors of the EFEM in the X and Y directions, the steps in block 290 may further include: i1 Analyzing coordinates of center points in the m third images to obtain total center point linear errors of the EFEM and the wafer bearing and moving platform in the X and Y directions; and i 2) obtaining a linear error of the EFEM in the X and Y directions based on both the total center linear error and the stage error. As an example, the step of i 2) above may more specifically comprise: subtracting the corresponding stage errors in the X and Y directions from the total circular linear error in the X and Y directions to obtain linear errors in the X and Y directions, respectively, of the EFEM.
It will be readily appreciated that the third image may be processed in step i) above to obtain linear errors in the X and Y directions of the EFEM in a manner similar to that described above for processing the n+1 first images.
For example, similarly, in some embodiments, the step i 1) above may further comprise: selecting one of m third images as a reference image; analyzing the position deviation of the center point of each other image in the m third images relative to the center point in the reference image; and the step i 2) may further include: subtracting the corresponding stage errors in the X and Y directions from the positional deviations corresponding to each other image to obtain linear errors in the X and Y directions for the EFEM corresponding to each other image; then, an error section may be constructed by taking the maximum value and the minimum value of the obtained linear errors after traversing m as the linear errors in the X and Y directions of the above-described EFEM.
In order to more clearly understand the above-mentioned linear error calculation method, it is assumed that the total center-to-center linear error of the EFEM and the wafer carrier and motion stage in the X and Y directions is respectively equal to (xm), (ym), where m represents the third image corresponding to the m-th image, and as mentioned above, the stage error of the wafer carrier and motion stage in the X and Y directions is equal to (X0), (Y0), and then for the third image of the m-th image, the difference between the total center-to-center linear error and the stage error can be expressed by the following formula
Xcm = fatx-x 0; ycm = faty-y 0 formula (1)
Further, father xcm and father xcm may be taken after traversing mMaximum and minimum values in both ycm to form a linear error interval [ min ] in the X and Y directions for EFEM ∆xcm, max ∆xcm ], [min ∆ycm, max ∆ycm ]。
For rotational errors of the EFEM in the R direction, the rotational errors may be calculated by way of the following several examples.
As a first example, the relevant steps of obtaining a rotation error in block 290 described above may include, for example: i3 Analyzing coordinates of the predetermined spin points of the m second images to obtain a total spin point error in both the X and Y directions for the EFEM and the wafer carrier and motion stage; and i 4) subtracting the total center-point linear error from the total spin point error to obtain a rotational error of the EFEM in the R direction.
It should be noted here that for a predetermined spin point, its total spin point error in the X and Y directions includes, in addition to the linear error of the EFEM in the X and Y directions and the stage error of the wafer carrier and motion stage in the X and Y directions, the rotational error of the EFEM in the R direction (which is reflected in the corresponding components in the X and Y directions). On the other hand, as previously described, it should be appreciated that the total center-to-center linear error may be comprised of both the linear error of the EFEM in the X and Y directions and the stage error of the wafer carrying and moving stage in the X and Y directions, and therefore, the X, Y component of the rotational error of the EFEM in the R direction or the rotational error may be obtained by simply subtracting the total center-to-center linear error from the total center-to-center linear error.
As a second example, the relevant steps of obtaining a rotation error in block 290 described above may include, for example: i5 A rotational error of the EFEM in the R direction is obtained based on an offset error analysis of each other of the m second images relative to the predetermined centrifugal point of the reference image.
More specifically, the step of i 5) above may for example comprise: selecting one image of the m second images as a reference image; obtaining an offset distance of the predetermined centrifugation point of each other image in the second image relative to the predetermined centrifugation point of the reference image after subtracting the linear error of the EFEM; and calculating a central angle corresponding to the offset distance based on the offset distance, wherein a rotation error of the EFEM in the R direction is represented by a section between a minimum value and a maximum value of the central angle.
To better understand the specific calculation process of i 5) above, FIG. 3 shows a schematic diagram of the rotational error in the R direction caused by the EFEM, where the A point represents the predetermined centrifugal point on the second image other than the reference image, the O point represents the center of the circle of the wafer, and the B point represents the predetermined centrifugal point of the reference image; point a 'represents the corrected point a, which subtracts the EFEM's own linearity error (father xcm, father ycm).
Further, it will be appreciated that angle AOB represents the total error angle due to the EFEM and wafer carrying and motion platform, angle AOA 'represents the central angle corresponding to the offset distance due to the EFEM's own linearity error (fatly xcm, fatly ycm), and angle A 'OB represents the central angle corresponding to the offset distance due to the EFEM's own rotation error.
Here, it is assumed that the coordinates of the point a are (X A ,Y A ) The coordinates of the point B are (X B ,Y B ) The coordinate error (or integrated error) of the predetermined off-center point a with respect to the point B in each second image may be expressed as ± xbm =x A -X B , ∆ybm=Y A -Y B . The coordinate error (or integrated error) of the A' point relative to the B point can be calculated by subtracting the linear error of the EFEM itself (fatter xcm, fatter ycm), namely fatter xbm-fatter xcm, fatter ybm-fatter ycm.
Accordingly, the distance between point a 'and B electricity |a' b| can be calculated as:
| A’B|=[(∆ xbm -∆ xcm ) 2 +(∆ ybm -∆ ycm ) 2 ] 1/2formula (2)
Let +.A' OB=αm, where m represents the mth second image, then there is
Wherein h is the distance from the point A' or the point B to the center of the wafer. Further processing equation (3), one can obtain:
Finally, the interval between the angle at which the numerical value is the largest and the angle at which the numerical value is the smallest, i.e., [ min αm, max αm ], may be taken as the rotational error of the EFEM in the R direction after traversing m in αm.
As a third example, the steps in block 290 described above may include, for example: i6 Identifying a predetermined straight line present on each second image; i7 Based on a slope analysis of the predetermined straight line on each second image, a rotational error of the EFEM in the R direction is obtained. As a non-limiting example, the predetermined straight line may be, for example, a predetermined straight line as a mark on the wafer.
More specifically, the step of i 7) above may further include: selecting one image of the m second images as a reference image; obtaining an angular error of the predetermined straight line of each other image in the second image relative to the predetermined straight line of the reference image; and taking an error interval formed by the maximum value and the minimum value of the angle errors as the rotation error of the EFEM in the R direction after traversing the m.
Here, for convenience of understanding, it is possible that the predetermined straight line of each of the other images in the above-described second image is represented by a straight line passing through O and a point, and the predetermined straight line of the reference image is represented by a straight line passing through O and B point, still referring to fig. 3.
In some embodiments, the slope of the predetermined straight line may be obtained, for example, by taking 2k points on the straight line, and finding a slope for each two points. And (3) injection: here, a sufficiently long distance between the two points may be required, the points from which the regression deviates are screened off, the remaining points are sloped and averaged.
Similarly, the angle error αm caused by the EFEM upper patch corresponding to the mth image may be obtained by comparison with the angle of the slope of the predetermined straight line of the reference image. Then, after traversing m in αm, a section between the angle where the numerical value is largest and the angle where the numerical value is smallest, that is, [ min αm, max αm ], may be taken as a rotation error of the EFEM in the R direction.
As a fourth example, the steps in block 290 described above may include, for example: i8 Identifying two corner points of a predetermined polygon present on each second image; i9 Determining the slope of the line connecting the two corner points; i10 Based on slope analysis of the links on each second image, a rotational error of the EFEM in the R direction is obtained. As a non-limiting example, the polygon may include a regular or irregular shape such as a rectangle, a square, a hexagon, etc., and the two corner points of the predetermined polygon may be, for example, lines of marks (e.g., two corner points of a square) on the wafer.
Similarly, step i 10) above may comprise: selecting one image of the m second images as a reference image; obtaining an angular error of a line in each other image in the second image relative to a line of the reference image; and taking an error interval formed by the maximum value and the minimum value of the angle errors as the rotation error of the EFEM in the R direction after traversing the m.
The flow of the method for determining the positioning accuracy of the wafer transfer apparatus according to the various embodiments of the present disclosure has been described in detail above. It will be appreciated that the method of the present disclosure has the following advantages:
1. hardware interference is eliminated: because one camera is adopted, the error of the image caused by the inconsistency of horizontal angles when a plurality of cameras are installed is avoided.
2. Excluding errors of the bearing table (note: bearing table contains no rotation axis, only X, Y direction errors): in the testing process, the errors in the X and Y directions of the wafer bearing and moving device are measured firstly, so that an error interval is obtained, errors caused by the wafer bearing and moving device are eliminated, and the linearity and the angular position accuracy of the EFEM when the EFEM is on the wafer are obtained more accurately.
3. And a large amount of data are tested, the mark point taking repeatability is high, and the testing precision is high: during data processing, point position coordinate data deviating from regression are screened out, an image processing algorithm is used, a mode of marking a plurality of groups of points of the straight line is adopted, the position between the upper point and the lower point is fitted, and therefore the center position of the straight line can be obtained more accurately, and the angle of the straight line is calculated through the points.
4. The test speed is high, the whole process is automatic, and the artificial interference is eliminated.
It will also be appreciated that the methods for determining the positioning accuracy of the wafer transfer apparatus of various embodiments of the present disclosure may be implemented by a wafer processing apparatus by which the positioning accuracy of the wafer transfer apparatus in the apparatus may be determined. Furthermore, the present disclosure relates to a computer readable medium storing computer readable instructions that, when executed by a processor, may cause an apparatus to perform a method for determining positioning accuracy of a wafer transfer device according to various embodiments of the present disclosure. The apparatus may be, for example, the wafer processing device mentioned above.
It will also be appreciated that the above described flow is merely an example. Although the steps of a method are described in a particular order in the specification, this does not require or imply that the operations must be performed in the particular order or that all of the illustrated operations be performed in order to achieve desirable results, and that the order in which the steps are described may be altered. Additionally or alternatively, certain steps may be omitted, multiple steps combined into one step to perform, and/or one step decomposed into multiple steps to perform.
While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.
In the claims, the word "comprising" does not exclude other elements, and the indefinite article "a" or "an" does not exclude a plurality. A single element or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain features are recited in mutually different embodiments or in dependent claims does not indicate that a combination of these features cannot be used to advantage. The scope of the present application encompasses any possible combination of the features recited in the various embodiments or the dependent claims without departing from the spirit and scope of the present application.
Furthermore, any reference signs in the claims shall not be construed as limiting the scope of the invention.
Claims (15)
1. A method of determining the positioning accuracy of a wafer transfer apparatus, comprising:
a) Receiving a single target wafer from an equipment front end module EFEM using a wafer carrier and motion platform;
b) Acquiring a first image of the single target wafer at a first predetermined position by using an imaging device;
c) Moving the single target wafer from the first predetermined position to a second predetermined position using the wafer carrying and moving stage;
d) Returning the single target wafer from the second predetermined position to the first predetermined position using the wafer carrying and moving stage;
e) Repeating steps b), c) and d) n times, thereby obtaining n corresponding first images, wherein n is an integer much greater than 1; and
f) And obtaining the platform errors of the wafer bearing and moving platform in the X and Y directions based on the n+1 first images.
2. The method as recited in claim 1, further comprising:
g) Receiving m target wafers from the EFEM one by one using the wafer carrier and motion stage and moving each of the m target wafers one by one to a third predetermined position, wherein m is an integer substantially greater than 1;
h) Acquiring second images of predetermined centrifugal points and third images of center points on each target wafer at the third predetermined positions one by using the imaging device, so as to obtain m corresponding second images and m third images, wherein the predetermined centrifugal points are predetermined points deviating from the center points of the corresponding target wafers; and
i) Based on the m second images and the m third images, a linear error of the EFEM in the X and Y directions and a rotational error in an R direction are obtained, where R represents a rotational direction.
3. The method according to claim 2, wherein the i) step comprises:
i1 Analyzing coordinates of center points in the m third images to obtain total center point linear errors of the EFEM and the wafer bearing and moving platform in X and Y directions;
i2 Based on both the total center point linear error and the stage error, linear errors of the EFEM in the X and Y directions are obtained.
4. A method according to claim 3, wherein the i 2) step comprises:
subtracting the corresponding stage errors in the X and Y directions from the total center linear error in the X and Y directions to obtain linear errors in the X and Y directions, respectively, of the EFEM.
5. The method according to any one of claims 3-4, wherein step i) further comprises:
i3 Analyzing coordinates of the predetermined spin points of the m second images to obtain a total spin point error in both the X and Y directions for the EFEM and the wafer carrier and motion stage;
i4 Subtracting the total center-point linear error from the total spin point error to obtain a rotational error of the EFEM in the R direction.
6. The method according to any one of claims 3-4, wherein step i) further comprises:
selecting one image of the m second images as a reference image;
obtaining an offset distance of a predetermined centrifugation point (a') of each other image in the second image relative to a predetermined centrifugation point (B) of the reference image after subtracting the linear error of the EFEM;
and calculating a central angle corresponding to the offset distance based on the offset distance, wherein a rotation error of the EFEM in the R direction is represented by a section between a minimum value and a maximum value of the central angle corresponding to the other image.
7. The method according to any one of claims 3-4, wherein the i) step comprises:
identifying a predetermined straight line present on each second image;
a rotational error of the EFEM in the R direction is obtained based on a slope analysis of the predetermined straight line on each second image.
8. The method according to any one of claims 3-4, wherein the i) step comprises:
identifying two corner points of a predetermined polygon present on each second image;
determining the slope of a connecting line of the two corner points;
a rotational error of the EFEM in the R direction is obtained based on a slope analysis of the link on each second image.
9. The method of any of claims 1-4, wherein the first predetermined location is a location where the wafer carrier and motion stage initially receives the single target wafer from the EFEM.
10. The method according to any one of claims 1 to 4, wherein in said e) step said second predetermined position is variable.
11. The method according to any one of claims 2 to 4, wherein the third predetermined position and the second predetermined position are different or identical to each other.
12. The method according to any one of claims 2 to 4, wherein the value of n is greater than 30 and the value of m is greater than 30.
13. The method of any one of claims 2 to 4, wherein the imaging device is a single camera.
14. A computer readable medium storing computer readable instructions which, when executed by a processor, cause a wafer processing apparatus to perform the method of any one of claims 1-13.
15. Wafer processing apparatus comprising a computer readable medium according to claim 14.
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| CN111554601B (en) * | 2020-04-27 | 2021-12-28 | 上海果纳半导体技术有限公司 | Wafer front end transfer system |
| CN114628301A (en) * | 2022-03-22 | 2022-06-14 | 北京半导体专用设备研究所（中国电子科技集团公司第四十五研究所） | Positioning precision determination method of wafer transmission system |
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